Conventionally, a cutting tool made of diamond-coated cemented carbide (hereinafter, referred to as “diamond-coated tool”) is known, in which a diamond film coats a tool body made of tungsten carbide (WC)-based cemented carbide (hereafter, referred to as “cemented carbide”). In a conventional diamond-coated tool, since the adhesion between a tool body and a diamond film is insufficient, various proposals for improvement of the adhesion have been made, where cobalt inhibiting a formation of diamond is removed from the surface of the tool body made of cemented carbide before forming the diamond film, and then the diamond film is formed on the tool body.
For example, PTL 1 discloses that in a diamond-coated tool, a cemented-carbide body is etched in stages so as to remove Co (cobalt) from a surface of a cemented-carbide body and form concaves and convexes with a size around the diameter of WC particles on the cemented-carbide body, and then a diamond film is deposited, thereby improving adhesion between the diamond film and the cemented-carbide tool body.
PTL 2 discloses that in a diamond-coated tool, an intermediate layer made of W (tungsten) or the like coats the cemented-carbide body on which the concaves and convexes are formed by electrolytic etching, and then the intermediate layer is coated with a diamond film, thereby improving adhesion between the diamond film and the tool body.
For example, PTL 3 discloses that before coating a cemented-carbide tool body with diamond, carbides of one or more metals selected from Groups IVa, Va, and VIa of the Periodic Table of elements, or ceramic particles such as silicon carbide, alumina are embedded into a surface of the cemented-carbide tool body. In PTL3, the surface of the cemented-carbide tool body is subjected to the electrolytic etching so as to have concave and convex surfaces, thereby improving adhesion between the tool body and the diamond film.